Question

[Lê Phương Thảo]

Cho hai biểu thức;

A=\(\frac{4}{7.31}+\frac{6}{7.41}+\frac{9}{10.41}+\frac{7}{10.57}\)

B=\(\frac{7}{19.31}+\frac{5}{19.43}+\frac{3}{23.43}+\frac{11}{23.57}\)

Tinh ti so \(\frac{A}{B}\)

Answer 1

[Hoang Hung Quan]

\(A=\frac{4}{7.31}+\frac{6}{7.41}+\frac{9}{10.41}+\frac{7}{10.57}\)

\(=\frac{20}{35.31}+\frac{30}{35.41}+\frac{45}{50.41}+\frac{35}{50.57}\)

\(=5\left(\frac{4}{35.31}+\frac{6}{35.41}+\frac{9}{50.41}+\frac{7}{50.57}\right)\)

\(=5\left(\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}\right)\)

\(=5\left(\frac{1}{31}-\frac{1}{57}\right)\)

\(B=\frac{7}{19.31}+\frac{5}{19.43}+\frac{3}{23.43}+\frac{11}{23.57}\)

\(=\frac{14}{34.31}+\frac{10}{38.43}+\frac{6}{46.43}+\frac{22}{46.57}\)

\(=2\left(\frac{7}{34.31}+\frac{5}{38.43}+\frac{3}{46.43}+\frac{11}{46.57}\right)\)

\(=2\left(\frac{1}{31}-\frac{1}{34}+\frac{1}{34}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}+\frac{1}{46}-\frac{1}{57}\right)\)

\(=2\left(\frac{1}{31}-\frac{1}{57}\right)\)

\(\Rightarrow\frac{A}{B}=\frac{5\left(\frac{1}{31}-\frac{1}{57}\right)}{2\left(\frac{1}{31}-\frac{1}{57}\right)}=\frac{5}{2}\)

Answer 2

[Trí Phạm]

Viết sai rồi\(\dfrac{1}{38}\)mà ghi\(\dfrac{1}{34}\)